1. Field of the Invention
The present invention relates to method and apparatus for transceiving audio data reproduced from a recording medium such as a digital versatile disk (DVD) through a digital interface such as IEEE 1394.
2. Description of the Related Art
The standardization for a recently developed disk-type recording medium, especially a digital versatile disk (referred as xe2x80x98DVDxe2x80x99 hereinafter) has been rapidly developed among related companies, so it is expected that a DVD is going to be widely used. Also, a digital video/audio reproducing apparatus capable of providing high-quality video and audio, for example, a digital TV (referred as xe2x80x98D-TVxe2x80x99 hereinafter) displaying high-quality digital video/audio signals reproduced from a DVD or received through a satellite will be popularized in the near future.
Accordingly, a method using a DVD player or a DVD recording/reproducing device in connection with a D-TV is expected to be rapidly increased, and a digital communication standard of IEEE 1394 which is sure to be adopted for data transmission between A/V apparatuses.
A data reproducer reproducing data recorded on a DVD differently processes digital data stream of MPEG format, especially a program stream (referred as xe2x80x98PSxe2x80x99 hereinafter) depending upon whether the data stream contains a presentation data or a navigation data. The presentation data is processed to yield video and audio, and the navigation data is used for controlling data reproducing operation of a DVD player.
Contrary to a DVD player, a D-TV processes digital data streams of MPEG format organized with transport streams (referred as xe2x80x98TSxe2x80x99 hereinafter) into presentation data, and converts them into video and audio signals. Accordingly, a DVD player should convert PS into TS before transmission, or a D-TV should convert received PS into TS before signal processing.
The difference between PS and TS is as follows.
The PS consists of several packs and each pack consists of packetized elementary stream (PES) packets containing digitized video, audio, and additional information data. A PES packet can contain data whose size is variable so that the size of a PES packet may not be same all the time.
On the contrary, the TS consists of transport packets and each packet has a fixed length of 188 bytes including its packet header.
Accordingly, when converting PS into TS, each PES packet of PS should be divided into packets of TS sequentially and necessary header information is added to each divided TS packet at that time. Because a PES packet is divided into multiple TS packets, remaining area of the last TS packet is stuffed with null data after writing all data of a PES packet in the multiple TS packets.
Audio data of high quality modulated in liner pulse code modulation (referred as xe2x80x98LPCMxe2x80x99 hereinafter) method may be included in digital data streams recorded in a DVD, so that a DVD player should convert LPCM audio data, if they are included in the reproduced digital data streams, into data packets whose format is able to be processed in a D-TV.
For such conversion, after a DVD player decodes LPCM audio data included in the data streams reproduced from a DVD, it re-encodes the decoded audio data into MPEG-formatted audio data or AC3-formatted audio data which is able to be processed in a D-TV, then transmits re-encoded audio data to a D-TV through a digital interface such as IEEE 1394.
Accordingly, a re-encoder is inevitably equipped in a DVD player for decoding LPCM audio data reproduced from a DVD and re-encoding them MPEG-formatted or AC3-formatted audio data. However, these decoding and re-encoding procedures requires additional hardware which increases manufacturing cost. Moreover, data processing is delayed and original LPCM audio data might be lost due to the re-encoding step.
It is an object of the present invention to provide method and apparatus for transceiving audio data stream through a digital interface, which are able to map specific formatted audio data, especially LPCM audio data reproduced from a recording medium such as a DVD into MPEG-formatted data streams without re-converting and transmit them at a transmitting side, check the received data streams on whether they includes LPCM audio, and retrieve and decode LPCM audio data inserted in the received data streams at a receiving side.
A method for transmitting audio data stream through a digital interface according to the present invention comprises the steps of separating audio data stream from data reproduced from a recording medium, inserting the separated audio data stream into the private data area of MPEG-formatted data stream, and transmitting the MPEG-formatted data stream containing audio data stream in the private data area through the digital interface.
A method for receiving audio data stream through a digital interface according to the present invention comprises the steps of checking whether or not a MPEG-formatted data stream received through the digital interface includes the private data area, extracting audio data inserted in the private data area, and decoding the extracted audio data.
A disk reproducing apparatus to which audio data stream transmitting method according to the present invention is applied comprises a detecting means for detecting digital data stream recorded in a recording medium; a separating means for separating audio data from the detected-data stream, a converting means for constructing MPEG-formatted data stream whose the private data area is packed with the separated audio data and converting the constructed stream into packets of transmittal format together with digital data stream of which audio data is separated; and a transmitting means for sending the packets of transmittal format through a digital communication interface.
An A/V apparatus to which audio data stream receiving method according to the present invention comprises a receiving means for receiving digital-data stream transmitted through a digital communication interface; a extracting means for checking whether the received MPEG-formatted data stream includes the private data area and extracting audio data inserted in the private data area; and a decoding means for decoding the extracted audio data.
In the present invention, the transmitting side inserts audio data, especially LPCM audio data reproduced from a disk-type recording medium such as a DVD into the private data area of a MPEG-formatted data stream, which may be distinguished from the MPEG-formatted video/audio data streams, and transmits through a digital communication line. The receiving side checks whether the data streams received through the digital communication line includes the private data area and then decodes LPCM audio data inserted in the private stream if there are LPCM audio data. According to the above procedures, the present invention can deliver high-quality LPCM audio data recorded in a recording medium to other device without re-encoding.